Poison
by kettleoat
Summary: What happens when a mind as ingenious as Sherlock Holmes' begins to tear itself apart? Oneshot for now, but I may continue it if I receive good feedback.
1. Chapter 1

'Hello, Sherlock.'

Sherlock turned. He was standing in the ruins of what once was a city, but was now a crumbling shell of its former magnificence: the tower blocks, their roofs scratching the sky, were open and hollow, gashes yawning in the flaking stone; the pavement was worn and split open, revealing pipes snaking like rusted veins beneath the surface, and weeds had burst through the fretwork of cracks that had spread across the road. Overturned cars were strewn amidst the rubble of collapsed buildings, shattered windows staring like unseeing eyes at the wreckage. Ash was falling silently through the air like snow, coating the ground with a thin, white layer that crunched underfoot.

'Who are you?' said a voice. It took Sherlock a moment to realise that it was his own.

'I am your nemesis,' said the man standing opposite him. He was dressed in a grey suit and tie, the shirt beneath crisp and white as the drifting ash. Despite the clouds of dust that rose with every step; despite the rust that coated the car he was leaning against, his clothes were miraculously clean and unblemished.

Sherlock stared across the street, feeling the ash settle in his hair and on his shoulders, watching as the man took a step closer to him. He walked with an odd, swaying gait, his hands thrust deep into his pockets, a smile playing on his mouth as he sauntered casually towards Sherlock.

'People say that you can't have enemies,' the man said, his dark eyes locking with Sherlock's. 'Apparently it doesn't happen any more.' He grinned, and his teeth glinted. 'But I know for a fact that I'm yours. Isn't that right, Sherlock?'

Sherlock didn't take his eyes off the man as he stopped a few feet from him. There was something about that face - those dark eyes - that he couldn't read.

'You can't do it, can you?' the man said, seeming to notice the slight flick of Sherlock's eyes up and down his body. 'You can't make any deductions about me.' He chuckled, bringing his hand up to his mouth like a child and biting the knuckles. 'It's because I'm different, Sherlock.'

Above them, black clouds were writhing, spreading like ink on a wet cloth across the sky.

The man took another step forward so that his face was close to Sherlock's, the black eyes still boring into the other's.

'I am your downfall,' he whispered.

Sherlock felt coldness seep into his chest like some noxious gas, spreading throughout his body so that every limb seemed leaden.

'Who are you?' he breathed.

The man grinned and his black eyes seemed to grow, the dark tunnels at the centres expanding so that his face was engulfed with shadow. The cityscape was disappearing, being eaten away by this terrible, crepuscular nothingness.

'Goodbye, Sherlock,' said the man's voice. 'They're calling for you. Can't you hear them?'

Sherlock staggered backwards, lashing out at the man, hearing his snide laughter echoing in the darkness, and -

'Sherlock!'

He opened his eyes.

There was a man staring at him, both his hands gripping Sherlock's wrists in a vicelike grip, his brow furrowed and anxious.

'What? Where am I?' Sherlock asked, sitting up.

The man looked more concerned than ever. 'We're in a taxi, going home. Don't you remember?'

Sherlock pressed his fists into his eyes and rubbed hard. The man seemed familiar to him, yet he could not quite remember his name.

Apparently he seemed unwell, for the man said, 'Are you alright?'

'Fine,' Sherlock said, still staring confusedly at him.

'Can you remember your name?' the man asked, still holding his wrists, though more gently now.

Sherlock blinked twice. 'Sherlock Holmes.'

'Well, at least you remember that much,' the man muttered, relaxing slightly. 'What about my name?'

Sherlock flinched. He could feel it on the tip of his tongue, waiting to be spoken. 'John - John Watson.'

'Everything seems in order,' John said, settling back into his seat with a sigh. 'I've never seen you sleep in a car before, let alone a taxi. Just tired?'

'No,' Sherlock said. He still felt dazed, though he was quickly regaining his efficient manner.

John blinked, frowned and turned his head to gaze briefly out of the window. Then he turned back, looking seriously at Sherlock. 'Thank you, by the way.'

Sherlock looked at him, surprised. 'What for?'

'For saving my ass from that bonfire, that's what for!' John said.

'Oh, yes,' Sherlock said, the memory flooding back. 'It was the only thing I could have done. Have you been checked over?'

'Lestrade brought an ambulance and they made sure I was alright. You were the one who told him to.'

'I did?'

'Ye-es, you did.'

'Unsurprising,' Sherlock said brusquely, turning his head slightly to watch the city blur past. He felt odd; his brain seemed to be moving very slowly, and there was a cold, sluggish weight seeping across his chest, just like in the dream.

The minutes ticked past. Sherlock felt his head droop, yet he didn't feel remotely tired. He could tell John was watching him and kept his body firmly upright. He didn't want to worry him unnecessarily.

After a while, John stopped the taxi a few streets away from Baker Street and they exited the vehicle. As they began the walk home, Sherlock realised that his symptoms were getting worse. He was finding it more and more difficult to stay upright, having to surreptitiously hold onto railings and walls, and the cold weight was spreading down his arms and legs. His vision was becoming blurred, and sounds boomed unnaturally loud.

When they reached a quieter, darker street not far off Baker Street, John stopped to call Mary and inform her that he was still alright. She had agreed to allow him to return to Baker Street for the night, as it was more convenient for a hospital in an emergency, and was going to visit the following morning.

As John talked on the phone, Sherlock leaned heavily against the railings, feeling numbness begin to fester in his chest. Something was wrong. These weren't the normal symptoms of exhaustion or illness.

A horrible suspicion dawned on him. As though in a trance, he drew the sleeve of his coat up his arm and undid the cuff of his shirt.

There was a small, red mark on his forearm. The veins around it were burning red through his skin, which seemed grey and sickly.

He had been poisoned.

'Sherlock?'

John had finished his phone call, and was moving towards him. 'Are you -'

'John,' Sherlock said. His voice seemed distant and far away. 'I think I've been drugged.'

John stared at him for a few moments. Then he took two quick steps forwards, seized Sherlock's arm and stared at the mark. Horror began to dawn on his face.

After a second, he looked up and said sharply, 'Are you experiencing any symptoms? Dizziness? Nausea? Blurred vision?'

'All of them,' Sherlock mumbled. He couldn't see John any more for the smears of colour that were swirling across his vision.

'Sherlock, I need you to stay awake. Can you do that for me?'

Sherlock gripped the railings tightly and tried to focus on John, but there was a roaring in his ears and darkness was leaking into his eyes.

'Sherlock? I need you to stay awake. Can you hear me?'

'Can't feel my hands,' Sherlock muttered.

He felt arms around him; felt him being supported into a sitting position on the cold ground. Pain was burning in his temples, making his brain slow and stupid.

'I need to call Lestrade, Sherlock. You have to stay awake for me. I'm right here.'

Sherlock grunted an affirmation, and after a moment he heard John talking urgently into his phone.

'Looks like he was drugged. Started about twenty minutes ago. He forgot where he was. Yes, I - no. Yes, alright.'

Sherlock felt a hand on his arm again and knew that John had crouched down beside him again. 'Lestrade's on his way, Sherlock. They're going to make sure you're alright, and then they're going to take you to the hospital so you can -'

'No!' Sherlock's eyes flew open, and he grabbed John's arm blindly. 'I'm not going there. Not going.'

'But Sherlock, you have to -'

'Baker Street,' he said, attempting to bring his eyes into focus. 'Antidotes there. Not hospital. Please.'

The roaring had become louder, blocking out all other noise so that he couldn't hear the cars on the distant road, or John's voice, or the wail of the police siren as Lestrade sped towards them on the busy streets of London. Sherlock wondered how long he had been sitting on this cold pavement; how long the drugs had been in his bloodstream.

'Lestrade's here,' he heard John say through the deafening roar. 'You're going to be alright now.'

Blackness was shrouding his eyes. He couldn't see; couldn't hear. His whole body felt cold and numb.

His head dropped onto his chest, and he felt himself falling into darkness. The last thing he heard before unconsciousness dragged him down was John's voice, echoing in the crushing blackness.

'SHERLOCK!'


	2. Chapter 2

' - erlock? Sherlock, can you hear me?'

Someone was shaking his shoulders lightly, making his head loll sideways onto his shoulder like a broken puppet. There was a heavy, aching sensation still clawing at his chest, and his hands felt much too big. He was vaguely aware of the rumble of a car engine; of anxious voices talking close by.

' - no idea what happened. We were walking back to Baker Street after the fire - he had been strange in the taxi, fell asleep, like I said - and then he just told me he had been drugged and that was it. He didn't say much before he passed out - something about not being able to feel his hands, but that was all. Oh, and he told me not to take him to a hospital, and to bring him to Baker Street. He said he had antidotes there.'

'Well, I can't say it surprises me,' said another voice, deep and grim. 'I'll bet you there are quite a few people out there who would like to see Sherlock Holmes incapacitated: all the people he's locked up, for a start.'

'Didn't lock them up,' Sherlock mumbled, his mouth seeming to find it difficult to get the words out. When he did speak, his voice sounded slurred, as though he was drunk. 'Merely provided...evidence. Didn't...take part in...locking up.'

'Sherlock!' The hands had seized his shoulders again, and he let out a low moan of pain as his throbbing head was jolted downwards. 'Oh, God, I'm sorry. How are you feeling?'

As the probing hands continued to grip his shoulders, Sherlock suddenly remembered that he had left his experiment - studying the use of electrolysis to isolate potassium - out on the table. He knew he shouldn't have gone to wash the flask before he had finished, thinking to return to it later, but he had been distracted by the fact that one of the eyeballs he had been boiling at increasingly high temperatures had burst. _89 degrees Celsius_, he thought vaguely, making a mental reminder to note that down.

'Left my experiment out,' he muttered, not managing to muster the energy to open his eyes. 'Potassium isolated via electrolysis...should have done strontium... Mrs Hudson hates it when I leave my experiments out. Eyeballs burst at 89 degrees. Should have written it down...'

'He's delirious,' Sherlock heard John's voice say, slightly muffled as though he had turned away.

'What the Hell has that drug done to him?' the other voice said angrily. Who was it? It was too deep to be Mrs Hudson's, and besides, this voice was male. He tried to think, but his mind had been wiped blank.

'Try to stay conscious, Sherlock, alright?' John said, squeezing his shoulders. 'Don't fall asleep on me now. We need you to try and stay awake.'

'Hang in there, mate,' the deep voice said, and Sherlock forced his eyes open a crack, just enough to see the grey hair and lined, weather-beaten face.

'We have visual contact,' the man said. 'You remember who I am, Sherlock?'

Sherlock shut his eyes and forced himself to _think_, to _remember_. He tried to open the door to his mind palace, but the handle would not turn. He tugged and wrenched at it, but to no avail. He was trapped: locked inside his own head.

'Sherlock?' said the man, and he realised that he had covered his face with his hands and that his eyes were screwed tight shut.

'No,' he said finally. 'I can't - I can't remember.'

There was a silence, and Sherlock gritted his teeth, trying to ignore the waves of pain that surged through his head with every movement.

'I can't remember,' he repeated, and as he spoke, panic washed over him in a tide that pressed him against the door of his mind-palace, crushing his lungs in fists of iron. He tried desperately to control his breathing, to remain calm, but the water was rising up his chest now, the waves lapping at his chin even as he beat on the door with his fists.

'Sherlock? Sherlock, calm down, it's alright, we've got you.'

The hands were back on his shoulders, although he had still not raised his head from his hands. He was vaguely aware of the fact that he was trembling, great shivers wracking his body and making him draw his coat tighter around him. He felt so cold.

'We need to hurry!' he heard John bark, and the other man's voice responding, 'I know, I know!'

Lestrade, that was it, he remembered suddenly, thinking of the name next to the speed-dial on his phone. His first name had slipped his mind - Graham? Gary? - but at least he had that one, small victory.

'What was it? Needle? Dart?' Sherlock heard Lestrade's voice say sharply.

'Needle,' John said. 'Though how whoever it was managed to first of all get within close enough proximity with Sherlock to jab him, and second to get the needle through his coat, is anyone's guess. I would have imagined that Sherlock would be paranoid of anyone getting close to him anyway, and after what happened with the bonfire, you would think he would be, if possible, more cautious.'

'Oh, I don't know,' Lestrade sighed. 'What are his symptoms?'

'From what he's told me, headache, nausea, general numbness most pronounced in the hands, fever, and,' - Sherlock felt two fingers press against his inner wrist - 'yes, accelerated pulse. I just hope that he has the right antidotes at Baker Street, and that he'll be alert enough to tell us where to find them.'

Sherlock shifted slightly in his seat, gripping his hair with shaking hands. Why was it so cold? John had said something about a fever: perhaps it was that which was causing him to huddle into his coat to try and retain some warmth.

'We're almost there, Sherlock,' came John's reassuring voice from beside him. Through the comforting façade, Sherlock could hear the anxiety and fear that layered his words.

'Coming around to Baker Street soon,' Lestrade chimed in. 'And then you can tell us where to find -'

But at that moment, a pain so terrible and blinding that it seemed like an atomic bomb in his mind exploded in his head, and suddenly he was falling down, down, down into a black chasm of agony. He could hear John shouting and his name being called, but the comforting note was gone, replaced by sheer panic. He felt his head smash against the window; felt himself thrashing wildly, his limbs seemingly out of his control. He was hammering on the door of his mind palace, screaming to be let in, but the floor had crumbled away and he was falling again, rushing backwards, away from John's frantic shouts and Lestrade's curses into the terrible, crushing blackness.


End file.
